Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
A capacitor is an electrical device that can store energy in the electric field between a pair of closely spaced conductors. When voltage is applied to the capacitor, electrical charges of equal magnitude, but opposite polarity, build up on each plate. The capacitance value of a capacitor is generally determined as proportional to the surface area of the parallel plates.
A supercapacitor (or ultracapacitor) can be an electrochemical double-layer capacitor that usually has high capacitance value when compared to common capacitors. This high capacitance value may be derived from using conductive materials of very high specific surface area. Most conventional supercapacitors use active carbon fiber cloth, active carbon particles or carbon fibers as electrode materials. These carbon materials are used because they have high theoretical specific surface area. With such high capacitance values, supercapacitors can be used as energy storage devices. Because supercapacitors typically have much less internal resistance than batteries, they are particularly suitable for providing transient power, for example providing a cold-cranking pulse power in electrical vehicles.